Greeting from a New Member and Norton Newbie

Thank you, guys.
L.A.B., as you mentioned, the holes are not tapped.
While the tile for the bike shows it as 1974 model, the engine and frame number is 306273, which shows as a 1973 Mk.1. I guess I should consider it a 1973 Mk. I, contrary to what the tile shows. I posted about this in more detail on another thread.

What does ”vernier” mean for these isolastics? Does it have to do with how to measure for adjustment/tuning? And is that what the Mk. III system is known as? Sorry to be dense about this!
 
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L.A.B. said:
A normal Commando characteristic (mentioned in the NOC Commando Service Notes) supposedly caused by the disc brake being on the right-hand side of the forks which can be cured by moving the brake to the left-hand side (by swapping over the fork legs and reversing the wheel) which was what the factory did on the 850 Mk3 but replaced the threaded bearing lockring with a circlip as the original lockring could potentially unscrew if the pre-Mk3 hub/wheel is reversed.

Or, just keep at least one hand on the bars.



Certainly not. :)
Click to expand...

I’ve been thinking about this, and can’t see how what side the disc is placed on will affect the tracking of the bike. Must be a gyroscopic thing……is this particular to the Norton Commando? I have ridden other bikes with single discs and never noticed it. Cheers!
 
The Vernier designation, , comes from the fact that the new mount is threaded and doesn't have shims so the setting is adjustable via the end plate nut which has a series of holes to allow quicker adjustment and setting i:e from right in against the cradle tight, then backed off to the recommended setting of 1 ½ holes out .
 
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Kane said:
I’ve been thinking about this, and can’t see how what side the disc is placed on will affect the tracking of the bike. Must be a gyroscopic thing……is this particular to the Norton Commando? I have ridden other bikes with single discs and never noticed it. Cheers!
Click to expand...

I don't think there has actually been a scientific explanation for this phenomenon but could be a gyroscopic effect.

You can read about it in the NOC Service Notes published in 1979 so it has been known about for some time.
http://www.billymegawatt.com/uploads/6/8/4/6/6846461/norton_750cc_service_notes.pdf
Page 29 & 30 (pdf pages 31 & 32).
 
Shelby-Right said:
The Vernier designation, , comes from the fact that the new mount is threaded and doesn't have shims so the setting is adjustable via the end plate which has a series of holes to allow quicker adjustment and setting i:e from right in and tight to the recommended setting of 1 ½ holes out .
Click to expand...
Awesome. Thank you!
 
L.A.B. said:
I don't think there has actually been a scientific explanation for this phenomenon but could be a gyroscopic effect.

You can read about it in the NOC Service Notes published in 1979 so it has been known about for some time.
http://www.billymegawatt.com/uploads/6/8/4/6/6846461/norton_750cc_service_notes.pdf
Page 29 & 30 (pdf pages 31 & 32).
Click to expand...
Thanks for the link to the service notes. So far it’s a good read! Kind of a trip about the left tracking phenomenon. My bike has a non-Norton front fork and brake, and the brake rotor is on the right leg, so barring anything being out of adjustment or a tweaked frame that I am not seeing which would cause the same thing to happen, my bike with hands off the bars drifts left as well. It’s not that bad, but it is noticeable. When the bike is ridden like a motorcycle rather than a unicycle there is no effect and it handles great.
 
Kane said:
Thanks for the link to the service notes. So far it’s a good read!
Click to expand...

Yes, although some information is rather dated now. Note there are some electronic copy errors in that pdf (plus the spelling has been changed from UK to US).
For instance on page 3: "126,125 FIRST COMMANDO, 17E( 3 'G4." should read FEB '68.
 
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You can use the Mk3 manual (section F) for checking/setting the vernier Isolastics.

 
Kane said:
Great. Thank you, L.A.B.
You and everyone here have been so helpful.
So, is it safe to say that the isolastics on my bike are Mk. III?
Click to expand...
Hi Kane, to echo others : welcome and yep, some REALLY clever and knowledgeable people here.
No such thing as a daft or crazy Q.
enjoy your good looking bike.
 
Kane said:
So, is it safe to say that the isolastics on my bike are Mk. III?
Click to expand...
Yes, although as I mentioned previously there's a minor difference between the front pre-Mk3 conversion kit and Mk3 vernier assemblies but the method of adjustment is the same and the rear vernier Iso. is the same as Mk3.
 
I should add that the early vernier front conversion kits required the pre-Mk3 mounting tube to be machined down to take the longer Mk3 threaded adjuster, therefore, it could possibly be that early type, however, once again, the adjustment is the same but I thought I'd mention it.
 
Dumb question: Where do you 'lever' on the engine to measure the isolastic clearances? Does it actually need levering?
 
Mart UK said:
Dumb question: Where do you 'lever' on the engine to measure the isolastic clearances?
Click to expand...

Anywhere that will push the engine (front) or cradle (rear) far enough over to remove all clearance from one side of the Iso. mount so the total clearance can be measured at the opposite end. Note the levering should be done with the through-bolt or stud fully tightened, and only slackened in order to make an adjustment.

Mart UK said:
Does it actually need levering?
Click to expand...

Yes and no. Yes, for the reason given above that the total clearance will then be at one end of the Iso. Alternatively, you could measure the clearance at both ends and add them together.

Or, no, because, personally, I don't bother with the levering as it can be as quick/easier to slacken the bolt or stud, insert the chosen size of feeler gauge (0.010") and with the threaded adjuster just in contact with the feeler, begin tightening the bolt or stud, checking at various stages that the feeler does not become clamped. If it does, then I slacken off the bolt/stud and back the adjuster off a little and continue until the bolt/stud is fully tightened with the feeler still free to slide.
If a note is made of the number of holes the adjuster has to be backed off from zero clearance then that method can also be used.
 
Kane said:
Great. Thank you, L.A.B.
You and everyone here have been so helpful.
So, is it safe to say that the isolastics on my bike are Mk. III?
Click to expand...
Kane,
Have you taken the rubber cover off to see what if anything other than the original setup you have on your bike?
Mike
 
Hi Mike,
here are pics of the front and rear. This is all new to me, but the consensus is that the bike has the Mk. III style. Two of the rubber boots have been removed and the two that are there are torn and in rough shape. Are the boots a benefit to have on the bike and worth replacing? Do the Internal rubber bushings degrade over time and need periodic replacement, and is there any maintenance to help those rubber parts last longer?
Cheers
 

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Kane said:
Are the boots a benefit to have on the bike and worth replacing?
Click to expand...

Some owners consider them to be water traps and do without them.

Kane said:
Do the Internal rubber bushings degrade over time and need periodic replacement,...
Click to expand...

Yes, they eventually degrade.

Kane said:
...and is there any maintenance to help those rubber parts last longer?
Click to expand...

Not really.

The front Iso. is also vernier.
 
L.A.B. said:
Some owners consider them to be water traps and do without them.



Yes, they eventually degrade.



Not really.

The front Iso. is also vernier.
Click to expand...
Great, good to know. The word “Vernier” is specific to the Mk. III system, and would not be used to describe pre-Mk. III?
 
Kane said:
Great, good to know. The word “Vernier” is specific to the Mk. III system, and would not be used to describe pre-Mk. III?
Click to expand...

Correct.
The standard pre-Mk3 Isolastics are adjusted by adding or removing shims...
andover-norton.co.uk

Andover Norton Parts Drawings - Genuine Andover Norton Factory Parts - Commando Parts

Andover Norton Parts are the only Norton spare parts in the market manufactured to original drawings, within the factory-approved tolerances, from the correct materials, and with the correct finish.
andover-norton.co.uk

...between the front mounting or cradle tube and the end caps...
andover-norton.co.uk

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.
andover-norton.co.uk
 

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